Drillable prepacked sand control liner



April 4, 1961 R. M. PITCHER ETAL 2,978,033

DRILLABLE PREPACKED SAND CONTROL LINER Filed April 1, 1957 FIG.- I

Richard M. Pitcher Elron A. Rose Inventors Warren 0. Sparks w 7 Arrorney nited States 2,978,933 Patented Apr. 4, 1961 2,978,033 DRILLABLE PREPACKED SAND CONTROL LINER Filed Apr. 1, 1957, Ser. No. 649,943

4 Claims. (Cl. 166-228) The present invention relates to a method and equip- "ment for the completion of oil, gas, or water wells. It relates more particularly to a drillable pre-packed well liner which is set in the well bore opposite at producing formation. Q

It is known in the art of producing hydrocarbons from underground reservoirs that many wells are drilled into or through loose or unconsolidated formations. When such a well is placed on production, sand is eroded from the formation and is carried into the well by the flow of fluid and is produced concurrently therewith. Thisentrained sand presents many producing and operatingproblems among those being severe erosionof the tubing, valves, and other equipment which are used in the production of oil and gas. In severe cases, suflicient sand may be carried from the formationwith the flow of formation fluids with the result that the overburden may crumble, thus filling the cavity through which the fluids are produced.- This crumbling of the overburdencan have the effect of stopping the flow of hydrocarbons from the producing formation to the well bore completely. This causes expensive work-overs and in some instances, even abandonment of the productive formation. In more severe casesthe casing may be caved in by. crumbling of the overburden resultingin the. loss of the entire well.

Multiple completions and. permanent type well completion are not practical where a large amount of sand is producedconcurrently with Oilipr gas; This type of duced passes primarily through the space or passageways between the ground shells. The path of the fluid flowing through the filler is quite tortuous with the direction of flow continually changing which knocks out or removes the entrained particles of sand from the fluid. The graded irregularly shaped walnut shell particles form a permeable packed filter which is both stable and durable to the production of oil, gas or water. The shells must be consolidated in place to prevent slumping. Slumping or settling of a filler normally occurs due to the liner being subjected to vibration or jarring while being lowered into place and can also be caused by fluid flowing through the liner. Slumping leaves large sections or passageways in the filter through which the fluid may travel which results in bypassing the tiller or filter and failure to remove the entrained sand. The consolidation or cementing in place of the ground walnut shells by the plastic prevents slumping" which would occur when the liner was loweredinto the well'if the shells were not bonded of oil and gas may be obtained. In some instances it may be desirable to remove the liner from the well bore.

completionis discouraged largely due to probable increased mechanicaldifficulties and failures. caused by the sand carried in thehydrocarbons. If sand is produced with "the hydrocarbons,fl surface equipment must be" inwells. a

Oneflofitheiobjectsof thisz inventi'on is to provide'a method and apparatus to eliminate the production of sand ,Qoncurrently with the production of oil, gas, or water.

A preferred embodiment of this invention utilizes two concentric perforated cylindersoffldilferent diameters fabricated of low density drillfable material such as aluminum or plastic. The annular space between the two concentric cylinders is packed with a filler of ground and graded walnut she ll.particlesconsolidated in place. or

stalled to remove the"'sa'nd beforethejhydroclarbons can be. further utilizedlf This problem ofsand control'is' also often encountered in the production of water from water 0 bondsbetween.the walnut shell particles. As the" alnut 7 shell particles are. slightly porous the plastic tends 'to enter or penetrateinto .theparticles thus producing a strong bonding effect. Theshells are coatedwith, plastic and are bonded together where" the shells come incontact prior to theset'ting of;t e plastici The tluid being pro the surface'to' producing formation 14- and is cemented in place'by cement'lti. 'Astr'ing'of tubing 18' is sues tion with the bore of the production tubing. Equalizing ports are provided at the upper end of the liner to equalize the pressure between thebore of the inner cylinder and the fluid in the Well bore which will prevent flow of drilling mud or other fluid through the filter as there will be no pressure differential across the filler while the liner is being lowered into place. The lower end of the inner perforated cylinder ispreferably provided with a check valve to permit flow of fluid downwardly through the bore of the inner cylinder which serves to aid in equalizing the pressure across the filler. The check valve is also used when it is necessary to wash out the liner and bore hole. Washing fluid may be circulated down through the check valve and up through the annulus as desired.

After the liner is in place the equalizing ports are closed. The flow of fluid from the producing formation rhust then be through the perforations in the outer or larger cylinder of the liner, through the filler of the consolidated walnut shell particles, through the perforations fof the. smaller cylinder of the liner and thence through.

the bore of the smaller perforated cylinder into the bore of the production tubing. 7 The prepacked liner will effectively filter out theentrained sand and permit only the productionof relatively sand-free fluid. If the production of sand is stopped, the possibility of any cave-in of the overburden is practically eliminated. The producing sand 7 itself although being unconsolidated will permit flow of oil and gas therethrough. Mechanical difliculties caused by sand erosionwill also be eliminated.

The nature and other objects of this invention will become apparent from the following detailed description of the accompanying drawing in which:

- Figure 1 illustrates a vertical section in diagrammatic form of a prepac'ked liner.

Figure 2 illustrates'an enlarged section of the walnut shell particles as they are bonded together.

Referring to the drawing in detail, number 19 designates a well bore hole in which casing 12: is set from and outer 24 is filled with a filler 26 of ground and graded walnut shell particles bonded together by a plastic or resin. Broadly the walnut shell particle must be of a size sufiicient to enable fluid flow between them and yet filter out the sand particles. The ground walnut shell particles may be graded between about 10-40 Tyler screen mesh. The particles should preferably pass through a screen size 10 but must not pass through a screen size 40. Screen size 10 has substantially square openings or passageways with the side dimension being .0937 inch and screen size 40 has substantially square openings or passageways with the side dimensions of .0165 inch. The preferred size is in the range of about 10-20. Screen size 20 has substantially square openings or passageways with the side dimension of .0331 inch.

The lower end of the prepacked liner 20 is provided with a guide shoe 28 which is used as an enclosure for the filler 26 and as a guide when lowering the prepacked liner 20. A check valve 30 is located in guide shoe 28 and serves to permit outwardly and downwardly flow of fluid especially while liner Z is being lowered. In the event a clean out of the well bore is necessary, water may also be circulated downward through check valve 30 without removing the liner. The prepacked liner 20 is attached to tubing 18 by adaptor 32. Adaptor 32 may normally be made of the same material as smaller cylinder 22. The adaptor 32 is provided with safety or left-handed threads at 31. If the liner becomes stuck the tubing can be unscrewed from the adaptor and liner. A cap or plug 34 is provided at the upper end of the prepacked liner 20 and serves to close the upper portion of the annular space between perforated cylinders 22 and 24. The cap may be made of neat cement, wood, rubber, plastic or any easily drilled'material which is impervious to and resistant to the fluid to be produced, resistant to the temperatures and pressures encountered and capable of sealing the annulus of the liner.

One or more equalizing ports 29 are provided in adap-- tor 32 at the top of liner 20 and serve to equalize the pressure between the fluid in the bore of cylinder 22 and the fluid within the well bore. A sleeve 33 is held in place in adaptor 32 by shear pins 35 while the liner 20 is being lowered. After the liner is in place a plug 38which may be a ball suspended by line 40 is lowered into and closes opening 42 in the top portion of sleeve 33. Hydrostatic pressure or other force may then be applied to shear pins 35 and force sleeve 33 downwardly thus closing ports 29. Sleeve 33 is closely fitted to adaptor 32 and will remain in the position in which it has been forced thus effecting the closure of ports 29. The ball is then withdrawn from the tubing by means of the line 40. Other means of closing ports 29 may of course be used.

A packer 36, such as a book wall type, if desired, may be set above adaptor 32 thus sealing the annular space between tubing 13 and casing 12; or if no packer is set, the annulus between the tubing and the casing is sealed at the surface. inner perforated cylinder 22 may be made of any low density drillable material of sufl'lcient strength and rigidity to support the filter. A suitable material is aluminum, or an oil and water resistant plastic such as ester-alkyd or the like. Inner cylinder 22 is perforated with the area of the perforations or holes being between about 10 and 60 percent of the exterior surface area. The perforations may be slotted, circular,

or any shape-desired. The material of the outer or larger cylinder 26 should be essentially the same characteristics as the material of the inner cylinder. The essential requirement is that the pipes or cylinders be readily drillable with conventional rotary drill bits. It should also be noted that all of the various parts of the prepacked liner should be drillable with the possible exception of the spring in the check valve which is relatively small and should cause no difficulty in removing.

Figure 2 illustrates in enlarged section the walnut shell particles bonded together by a film of plastic and also illustrates the passageways between the shells. The walnut shell particles 50 are coated with a film of plastic 41 and are bonded together where the particles come into proximate contact as at 52 before the plastic has set. It should be noted that the film or coating of plastic is very thin and forms practically no obstruction in passageway 44. It is through passageways 44 that the produced fluid passes as it flows through filler 26.

A preferred plastic used in this invention for the bonding of the ground walnut shells is a pheno-formaldehyde type. The ground walnut shells are sprayed with, or dipped into, a liquid plastic. The excess plastic is removed and the ground walnut shells are then packed in a partially assembled liner. The prepacked liner 20 is assembled with the exception of cap or plug 34, and the walnut shell particles which have been coated with plastic are poured into and packed in the annular space between the small cylinder 22 and large cylinder 24 before the plastic has set. Cap 34 is then placed or set in position, sealing the top of the annular chamber in which the walnut shell particles have been placed. Cap 34 may be a sealant such as neat cement which is essentially impermeable to fluid flow and poured into the annular space on top of the consolidated shells and permitted to set before being used. The prepacked liner may be assembled in other ways, for example, such as preforming or molding the filler, and after the plastic has set the filler is then placed in the annular space or chamber of the liner.

After the prepacked liner 20 is fabricated, it may be attached to a string of producing tubing by adaptor 32 for lowering into position. Sleeve 33 is held in position by shear pins 35 with equalizing ports 29 remaining open. Fluid in the well bore may then flow through ports 29 into the bore of cylinder 22 thus equalizing the pressure of the fluid within the bore of cylinder 22 and the fluid in the well bore. As there is now no pressure differential across the annular pack or filler there will be substantially no flow through the filler during the lowering of liner 20 into position.

After the liner is positioned opposite the producing formation, plug 38 is lowered into the opening in top of sleeve 33. Hydrostatic pressure may then be applied which will shear shear pins 35 and sleeve 33 will be forced downward closing ports 29; Check valve 30 in the bottom of liner 20 permits outward flow only from the bore of inner cylinder 22. Fluid from the producing formation to be produced must flow through the perforations of outer cylinder 24 and then through filler 26 which removes the entrained sand. The substantially sand free fluid then flows through perforation 23 into the bore of the inner cylinder 22 and then produced through the tubing in a conventional manner. 7

It is apparent that changes and modifications of this invention as hereinbefore set forth may'be made without departing from the spirit and scope thereof and only such limitations should be imposed as are indicated in the subjoined claims.

We claim:

1. A prepacked liner for wells comprising in combination a perforated smaller tubular member, a larger perforated tubular member surrounding said smaller tubular member, said smaller tubular member and said larger tubular member being made of a low density drillable material, a filler for the annular space between said smaller tubular member'and said larger tubular memher, said filler comprising ground walnut shells cemented in place by a plastic, a check-valve at the lower end of said liner, an adaptor with closable equalizing ports, a means for closing said ports, means for closing the annular space at the lower end and upper end whereby fiuid flowing from the producing formation passes through the perforations in said larger tubular member, said filler, and the perforations of said smaller tubular member.

2. A prepacked liner for a well comprising in combination a first drillable perforated tubular member, a second drillable perforated tubular member surrounding said first tubular member and defining an annular space therebetween, drillable means for sealing each end of the annular space, filtering means filling said annular space, said filtering means comprising particles of walnut shells bonded together in place by means of a plastic coating on each shell particle, a drillable adaptor on one end of the inner tubular member attached to a string of Well pipe, closable ports within the wall of the adaptor operable to provide fluid communication therethrough, means for closing said ports, a drillable check valve in the opposite end of said first tubular member adapted to enable fluid to flow selectively out of said first tubular member, said plastic coating being substantially impervious to water and hydrocarbons.

3. A prepacked liner supported from a tubular support member in a well bore comprising in combination a first perforated tubular member, a larger perforated tubular member surrounding said first tubular member and defining an annular space therebetween, said first tubular member and said larger tubular member being made from a material readily drillable by earth-boring tools, a filler for said annular space comprising ground Walnut shells cemented in place by a plastic coating on each shell particle, means for closing the annular space at the lower end and at the upper end, a check valve at the lower end of said first tubular member and of a character to prevent flow from outside said borehole into said first tubular member, an adapter for connecting said first tubular member to said tubular support member, pressure equalizing ports in said adapter, a sleeve fitted Within said adapter, shear pin for holding said sleeve above said ports and means for shearing said pin and for forcing said sleeve downwardly thus closing said equalizing ports.

4. A prepacked liner for wells comprising in combination a perforated smaller tubular member; a larger perforated tubular member surrounding said smaller tubular member; said smaller tubular member and said larger tubular member being made of material readily drillable with earth boring tools; a filler for the annular space between said smaller tubular member and said larger tubular member, said filler comprising ground walnut shells permanently consolidated together in the annular space by a plastic immiscible with and resistant to aqueous and hydrocarbon fluid; means to prevent fluid flowing into the lower end of said smaller tubular member; an adapter with closable equalizing ports attached to the upper end of said smaller tubular member; and means for closing said port.

References Cited in the file of this patent UNITED STATES PATENTS OTHER REFERENCES Henderson: Now Plastic-Coated Walnut Shells Control Loose Sands, World Oil, pp. 271, 2, 4, 6, April 1956. a 

